-52.95% is the change from 831 to 391
Calculation steps:
[( 391 - 831 ) ÷ 831] x 100 = -52.95%
Formula
Percentage change = [(391 - 831) / 831] x 100
Subtract the new number by the original number
391 - 831 = -440
-440 ÷ 831 = -0.529482551143201
-0.529482551143201 x 100 = -52.95%